Hey Kuritiusu! Hope these help out,
1) こわくて I'm guessing comes from 怖い (こわい) and is the connective form
2) hmm, 瞳 is sometimes a kind of romantic way of saying eyes, so maybe "we had the same eyes" ouch, painful, maybe "we had the same look in our eyes" but not sure..
3) this is a negative in the connective form, so, "can't reach"
4) けんかしようよ! all that comes to mind is "kenka" as in fight, and "shiyo" as in, lets..does that make any sense in the context it's in?